04 2500 crew cab 2wd just turned 50-K and broke through the 19 mpg barrier. City driving, no towing, avg. 500 lb cargo. Last time I towed it was about 14 city, when I am running the A/C I loose another mpg.

“If I accept you as you are, I will make you worse; however, if I treat you as though you are what you are capable of becoming, I help you become that.”

13MPG average towing 13,500GTWR city with the air conditioning on max
16MPG average towing interstate.

I can never get a true non-towing MPG average always towing something with each tank of diesel. If i had to guess it would be maybe max 18MPG

I am going to call BS on anything over 21MPG; because Diesel Power magazine has done a MAX MPG diesel challenge yearly, with diesel truck owners all over the county entering. The winner had over 10,000 dollars in engine modifications; which got a regular cab 2wd Durmax 21MPG no trailer highway. The overhead computers are not that accurate, Diesel Power has tested those what a joke.